The focus of the proposed research is the examination of the effect of ethanol on telencephalic neuron development and on the formation of synapses using the olfactory bulb as a model system. The olfactory bulb is an excellent system to study because it is a part of the telencephalon that is well understood morphologically and physiologically. Olfactory bulbs will be isolated postnatally from guinea pigs exposed to high, moderate and low levels of ethanol during the period of rapid neuronal development which in the guinea pig is prenatal, which is closer to human development. Differences in development of the olfactory bulb layers and the number of neurons in these layers will be monitored by light microscopy. Electron microscopic examination with morphometric analysis of synaptogenesis will be performed focusing on the density of synapses, the percentage of covering of neuronal surfaces by synapses and the maturity of synapses. The percentage of different types of synapses will be determined as well as the source of the pre- and post-synaptic elements. The possible causes of any changes in synaptogenesis will be investigated. Other alterations in neuronal morphology contributable to ethanol will be noted and if necessary will be quantified. Dose dependency of any ethanol induced changes will be determined. These experiments will provide vital information on the effect of ethanol on central nervous system development and will help to determine if ethanol can cause changes in neuronal development and specifically synaptogenesis, changes which might account for mental retardation and/or behavioral changes apparent in the Fetal Alcohol Syndrome in humans. Examination of ethanol effects on the Central Nervous System development in rodents and the development of a better rodent model for studying these effects seems warranted in view of the high percentage of birth defects including mental retardation in human attributable to ethanol consumption during pregnancy.